1. Field of the Invention
The present invention is generally related to photoelectric devices and, more particularly, to photoelectric devices which incorporate one or more lenses as an integral part of the housing structure for its photoelectric components.
2. Description of the Prior Art
Many types of devices for housing photoelectric components are well known to those skilled in the art. These devices can be constructed to house either single components, such as a light emitting element or a photosensitive element, or they can be constructed to house both light providing components and light sensitive components in a single housing structure. In addition, the photoelectric devices can be designed to use various types of light, such as infrared light, when a particular application requires it.
U.S. Pat. No. 4,553,033, which issued to Hubble et. al. on Nov. 12, 1985, describes an infrared reflectance densitometer. The device comprises a substrate which supports a light emitting diode, or LED, a control photodiode to compensate for component degradation, a background photodiode to compensate for background radiation and a large area photodiode to provide an electrical signal representative of the amount of toner particles on the photosensitive surface. The substrate is also used to carry a field lens which focuses light rays that are reflected from the photosensitive surface onto the signal photodiode. Also carried on the substrate is an aperture box which permits a portion of the LED light to project through the collimating lens to the photosensitive surface and a portion of the light to be reflected onto the control photodiode to control light output.
U.S. Pat. No. 4,812,003, which issued to Dambach et. al. on Mar. 14, 1989, discloses an optic sensing assembly. The assembly is intended to detect light reflection at a target area. It includes a cable holding element formed as an integral, one-piece body having sockets for directly receiving nonterminated ends of a light supply fiber optic cable and a light receiving fiber optic cable. Stop portions in the sockets accurately position the fiber optic cable ends. The housing is provided with a cavity for receiving the holding element and latch structures on the holding element and housing engage with each other to secure the holding element with stop portions positioned at a precise location relative to the housing. A strain relief structure is effective upon engagement of the latch structures for holding fiber optic cable ends within the sockets. An aperture in the housing communicates with the cavity for permitting light transmission between the cable ends and the target area. A lens structure formed integrally in the holding element directs or focuses light along paths from the cable ends to the target area.
When photoelectric devices are used in an industrial environment, they can come into contact with various types of fluids which may have a deleterious affect on the components and circuits contained within the housing of the photoelectric device. This situation is exacerbated in applications where frequent cleaning with high pressure hoses is used to assure a high degree of cleanliness with respect to the machinery or equipment with which the photoelectric devices are used. When the housing of a photoelectric device is subjected to a high velocity stream of liquid, which can comprise a cleaning solution, the liquid can enter internal portions of the photoelectric device unless the housing is specifically structured to prevent this. Although there are many techniques that can be employed to discourage the liquid from entering the internal portions of the photoelectric device, these techniques usually raise the cost of the photoelectric device and, in some cases, are not perfectly effective in protecting the photoelectric and electronic components contained within the housing structure.
The techniques known to those skilled in the art for providing a water tight housing for use in association with photoelectric components comprise the application of gaskets or O-rings and the careful configuration of mating parts in the housing. When two parts of a housing are to be associated together in contact relation, those parts are usually provided with threaded holes to allow them to be rigidly attached to each other and, in addition, the parts of the housing are shaped to receive a gasket or O-ring between them to further create an effective liquid seal. Although these techniques are generally effective in preventing liquid from intruding into the internal cavity of the housing, they can increase the cost and assembly time of the photoelectric device.
To decrease the cost of water tight housings, the number of components and the manufacturing steps required to produce the photoelectric device must be decreased. The present invention is directed to solve these problems described above and providing a simplified, but liquid tight, housing for a photoelectric device.